Inventions

6117 KiB

Open AccessArticle

Design Process Control for Improved Surface Finish of Metal Additive Manufactured Parts of Complex Build Geometry

by Mikdam Jamal and Michael N. Morgan

Inventions 2017, 2(4), 36; https://doi.org/10.3390/inventions2040036 - 13 Dec 2017

Cited by 20 | Viewed by 7465

Metal additive manufacturing (AM) is increasingly used to create complex 3D components at near net shape. However, the surface finish (SF) of the metal AM part is uneven, with surface roughness being variable over the facets of the design. Standard post-processing methods such [...] Read more.

Metal additive manufacturing (AM) is increasingly used to create complex 3D components at near net shape. However, the surface finish (SF) of the metal AM part is uneven, with surface roughness being variable over the facets of the design. Standard post-processing methods such as grinding and linishing often meet with major challenges in finishing parts of complex shape. This paper reports on research that demonstrated that mass finishing (MF) processes are able to deliver high-quality surface finishes (Ra and Sa) on AM-generated parts of a relatively complex geometry (both internal features and external facets) under select conditions. Four processes were studied in this work: stream finishing, high-energy (HE) centrifuge, drag finishing and disc finishing. Optimisation of the drag finishing process was then studied using a structured design of experiments (DOE). The effects of a range of finishing parameters were evaluated and optimal parameters and conditions were determined. The study established that the proposed method can be successfully applied in drag finishing to optimise the surface roughness in an industrial application and that it is an economical way of obtaining the maximum amount of information in a short period of time with a small number of tests. The study has also provided an important step in helping understand the requirements of MF to deliver AM-generated parts to a target quality finish and cycle time. Full article

(This article belongs to the Special Issue Modern Grinding Technology and Systems)

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2018 KiB

Open AccessArticle

Parametric Study of an Air Charged Franchot Engine with Novel Hot and Cold Isothermalizers

by Jafar M. Daoud and Daniel Friedrich

Inventions 2017, 2(4), 35; https://doi.org/10.3390/inventions2040035 - 05 Dec 2017

Cited by 3 | Viewed by 5129

Abstract

The Stirling engine is an external combustion engine that uses heat exchangers to enhance the addition and removal of energy. This makes the engine power-dense but expensive, less efficient and complicated. In this contribution, the Stirling engine based on the Franchot engine has [...] Read more.

The Stirling engine is an external combustion engine that uses heat exchangers to enhance the addition and removal of energy. This makes the engine power-dense but expensive, less efficient and complicated. In this contribution, the Stirling engine based on the Franchot engine has novel cylindrical fins working as isothermalizers to improve heat transfer without the complications of heat exchangers. Enhancing the power density by isothermalizing work spaces is compared to the bare cylinder optimized by varying the phase angle. The theoretical analysis shows that both the adiabatic and isothermal fins increase the power and efficiency, achieving the Curzon and Ahlborn efficiency at the maximum power point. In comparison to the phase angle method, the finned engine resulted in much lower gas mass flow rate, which leads to a reduction in the regenerator pumping and enthalpy losses. Thus, the Stirling engine has the potential to be simple, cheap, efficient and power-dense, and thus can be used effectively for different applications. Full article

(This article belongs to the Section Inventions and Innovation in Energy and Thermal/Fluidic Science)

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6990 KiB

Open AccessArticle

Influence of the Grinding Wheel Topography on the Thermo-Mechanical Stress Collective in Grinding

by Sebastian Barth and Fritz Klocke

Inventions 2017, 2(4), 34; https://doi.org/10.3390/inventions2040034 - 04 Dec 2017

Cited by 13 | Viewed by 6203

Abstract

The grinding process is used for both high-performance machining and surface finishing of hardened steel. In addition to the grinding parameters and the grinding fluid supply, the topography of the grinding wheel mainly determines the grinding process behavior and the grinding process result. [...] Read more.

The grinding process is used for both high-performance machining and surface finishing of hardened steel. In addition to the grinding parameters and the grinding fluid supply, the topography of the grinding wheel mainly determines the grinding process behavior and the grinding process result. An alteration of the topography by a variation of the volumetric composition of the grinding wheel, by a variation of the grinding wheel conditioning, or by wear causes a change in the contact conditions. The state of the art shows a substantial knowledge deficit about the influence of the volumetric grinding wheel composition and the resulting grinding wheel topography on the thermo-mechanical stress collective acting on the workpiece external zone. Thus, it is not possible to make a quantitative statement about the influence of the volumetric grinding wheel composition on the external zone properties of a component after grinding. Therefore, the aim of the current research is an empirical-analytical model for the prediction of the thermo-mechanical stress collective as a function of the grinding wheel topography. For this purpose, a methodology is developed, which enables the prediction of the topography-dependent thermo-mechanical load in a grinding process. Therefore, the topography is characterized by means of quantitative parameters and the main influencing variables on the grinding process behavior are investigated. The findings are used to analyze the influence of a change in the topography on the grinding temperature and the grinding force. The obtained results are summarized and are used to explain the thermo-mechanical stress collective as a function of the grinding wheel topography. Full article

(This article belongs to the Special Issue Modern Grinding Technology and Systems)

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4347 KiB

Open AccessArticle

Structuring Surfaces by Microfinishing Using Defined Abrasive Belts

by Meik Tilger, Monika Kipp, Sebastian Schumann, Tountzer Tsagkir Dereli and Dirk Biermann

Inventions 2017, 2(4), 33; https://doi.org/10.3390/inventions2040033 - 29 Nov 2017

Viewed by 5273

Abstract

Microfinishing, also known as superfinishing or short-stroke honing, is a commonly used process for generating technical surfaces focusing on tribological applications. Due to microfinishing processes high surface qualities are manufacturable regarding the surface roughness and bearing area ratio. While the required characteristics for [...] Read more.

Microfinishing, also known as superfinishing or short-stroke honing, is a commonly used process for generating technical surfaces focusing on tribological applications. Due to microfinishing processes high surface qualities are manufacturable regarding the surface roughness and bearing area ratio. While the required characteristics for tribological loaded workpieces are changing with their rising significance, the surface structuring is becoming more and more important. With the use of defined abrasive belts, the possibilities of surface structuring by microfinishing are enhanced. The possibilities and challenges concerning surface structuring by microfinishing applying defined abrasive belts are described in this research study. Therefore, a geometrical-kinematic simulation is used to predict the theoretical structures generated by microfinishing, while in experimental investigations the influences of kinematic parameters and a multi-stage process sequence are considered. Full article

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7464 KiB

Open AccessArticle

Activity-Aware Physiological Response Prediction Using Wearable Sensors

by Namita Lokare, Boxuan Zhong and Edgar Lobaton

Inventions 2017, 2(4), 32; https://doi.org/10.3390/inventions2040032 - 21 Nov 2017

Cited by 5 | Viewed by 5822

Abstract

Prediction of physiological responses can have a number of applications in the health and medical fields. However, this can be a challenging task due to interdependencies between these responses, physical activities, environmental factors and the individual’s mental state. In this work, we focus [...] Read more.

Prediction of physiological responses can have a number of applications in the health and medical fields. However, this can be a challenging task due to interdependencies between these responses, physical activities, environmental factors and the individual’s mental state. In this work, we focus on forecasting physiological responses in dynamic scenarios where individuals are performing exercises and complex activities of daily life. We minimize the effect of environmental and physiological factors in order to focus on the effect of physical activities. In particular, we focus on forecasting heart rate and respiratory rate due to their relevance in medical and fitness training. We aim to forecast these physiological responses up to 60 s into the future, study the effect of different predictors that incorporate different sensing modalities and different amounts of historical data and analyze the performance of various strategies for prediction. Activity information is incorporated by clustering the data streams and fitting different predictive models per cluster. The effect of clustering is also studied by performing a hierarchical analysis on the clustering parameter, and we observe that activity clustering does improve the performance in our proposed methodology when predicting physiological response across modalities. Full article

(This article belongs to the Special Issue Frontiers in Wearable Devices)

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5663 KiB

Open AccessArticle

Stochastic Kinematic Process Model with an Implemented Wear Model for High Feed Dry Grinding

by Michal Kuffa, Fredy Kuster and Konrad Wegener

Inventions 2017, 2(4), 31; https://doi.org/10.3390/inventions2040031 - 16 Nov 2017

Cited by 2 | Viewed by 5187

Abstract

This paper considers heavy duty grinding with resin bonded corundum grinding wheels and without lubrication and cooling. A vertical turning machine redesigned to a grinding machine test bench with a power controlled grinding spindle is used in all of the experiments, allowing high [...] Read more.

This paper considers heavy duty grinding with resin bonded corundum grinding wheels and without lubrication and cooling. A vertical turning machine redesigned to a grinding machine test bench with a power controlled grinding spindle is used in all of the experiments, allowing high tangential table feed rates up to 480 m/min. This special test-rig emulates the railway grinding usually done by a railway grinding train. The main test-rig components are presented and the resulting kinematics of the experimental set-up is described. A stochastic kinematic grinding model is presented. A wear model that is based on the kinematic description of the grinding process is set up. Grain breakage is identified as the main wear phenomenon, initiated by grain flattening and micro-splintering. The wear model is implemented into the stochastic kinematic modelling. The workpiece material side flow and spring back are considered. The simulation results are validated experimentally. The workpiece surface roughness is compared and a good agreement between simulation and experiment can be found, where the deviation between the experiment and the simulation is less than 15% for single-sided contact between the grinding wheel and the workpiece. Higher deviations between simulation and experiment, up to 24%, for double-sided contact is observed. Full article

(This article belongs to the Special Issue Modern Grinding Technology and Systems)

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1008 KiB

Open AccessArticle

Energy Storage Scheduling with an Advanced Battery Model: A Game–Theoretic Approach

by Matthias Pilz, Luluwah Al-Fagih and Eckhard Pfluegel

Inventions 2017, 2(4), 30; https://doi.org/10.3390/inventions2040030 - 16 Nov 2017

Cited by 13 | Viewed by 5469

Abstract

Energy storage systems will play a key role for individual users in the future smart grid. They serve two purposes: (i) handling the intermittent nature of renewable energy resources for a more reliable and efficient system; and (ii) preventing the impact of blackouts [...] Read more.

Energy storage systems will play a key role for individual users in the future smart grid. They serve two purposes: (i) handling the intermittent nature of renewable energy resources for a more reliable and efficient system; and (ii) preventing the impact of blackouts on users and allowing for more independence from the grid, while saving money through load-shifting. In this paper we investigate the latter scenario by looking at a neighbourhood of 25 households whose demand is satisfied by one utility company. Assuming the users possess lithium-ion batteries, we answer the question of how each household can make the best use of their individual storage system given a real-time pricing policy. To this end, each user is modelled as a player of a non-cooperative scheduling game. The novelty of the game lies in the advanced battery model, which incorporates charging and discharging characteristics of lithium-ion batteries. The action set for each player comprises day-ahead schedules of their respective battery usage. We analyse different user behaviour and are able to obtain a realistic and applicable understanding of the potential of these systems. As a result, we show the correlation between the efficiency of the battery and the outcome of the game. Full article

(This article belongs to the Section Inventions and Innovation in Electrical Engineering/Energy/Communications)

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5846 KiB

Open AccessArticle

Experimental Analysis for the Use of Sodium Dodecyl Sulfate as a Soluble Metal Cutting Fluid for Micromachining with Electroless-Plated Micropencil Grinding Tools

by Peter A. Arrabiyeh, Martin Bohley, Felix Ströer, Benjamin Kirsch, Jörg Seewig and Jan C. Aurich

Inventions 2017, 2(4), 29; https://doi.org/10.3390/inventions2040029 - 10 Nov 2017

Cited by 15 | Viewed by 5606

Abstract

Microgrinding with micropencil grinding tools (MPGTs) is a flexible and economic process to machine microstructures in hard and brittle materials. In macrogrinding, cooling and lubrication are done with metal cutting fluids; their application and influence is well researched. Although it can be expected [...] Read more.

Microgrinding with micropencil grinding tools (MPGTs) is a flexible and economic process to machine microstructures in hard and brittle materials. In macrogrinding, cooling and lubrication are done with metal cutting fluids; their application and influence is well researched. Although it can be expected that metal cutting fluids also play a decisive role in microgrinding, systematic investigations can hardly be found. A metal cutting fluid capable of wetting the machining process, containing quantities as small as 0.02% of the water-soluble fluid sodium dodecyl sulfate was tested in microgrinding experiments with MPGTs (diameter ~50 µm; abrasive grit size 2–4 µm). The workpiece material was hardened 16MnCr5. Full article

(This article belongs to the Special Issue Modern Grinding Technology and Systems)

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5276 KiB

Open AccessArticle

Impacts of Voltage Control Methods on Distribution Circuit’s Photovoltaic (PV) Integration Limits

by Anamika Dubey

Inventions 2017, 2(4), 28; https://doi.org/10.3390/inventions2040028 - 25 Oct 2017

Cited by 16 | Viewed by 6412

Abstract

The widespread integration of photovoltaic (PV) units may result in a number of operational issues for the utility distribution system. The advances in smart-grid technologies with better communication and control capabilities may help to mitigate these challenges. The objective of this paper is [...] Read more.

The widespread integration of photovoltaic (PV) units may result in a number of operational issues for the utility distribution system. The advances in smart-grid technologies with better communication and control capabilities may help to mitigate these challenges. The objective of this paper is to evaluate multiple voltage control methods and compare their effectiveness in mitigating the impacts of high levels of PV penetrations on distribution system voltages. A Monte Carlo based stochastic analysis framework is used to evaluate the impacts of PV integration, with and without voltage control. Both snapshot power flow and time-series analysis are conducted for the feeder with varying levels of PV penetrations. The methods are compared for their impacts on (1) the feeder’s PV hosting capacity; (2) the number of voltage violations and the magnitude of the largest bus voltage; (3) the net reactive power demand from the substation; and (4) the number of switching operations of feeder’s legacy voltage support devices i.e., capacitor banks and load tap changers (LTCs). The simulation results show that voltage control help in mitigating overvoltage concerns and increasing the feeder’s hosting capacity. Although, the legacy control solves the voltage concerns for primary feeders, a smart inverter control is required to mitigate both primary and secondary feeder voltage regulation issues. The smart inverter control, however, increases the feeder’s reactive power demand and the number of LTC and capacitor switching operations. For the 34.5-kV test circuit, it is observed that the reactive power demand increases from 0 to 6.8 MVAR on enabling Volt-VAR control for PV inverters. The total number of capacitor and LTC operations over a 1-year period also increases from 455 operations to 1991 operations with Volt-VAR control mode. It is also demonstrated that by simply changing the control mode of capacitor banks, a significant reduction in the unnecessary switching operations for the capacitor banks is observed. Full article

(This article belongs to the Special Issue Inventions and Innovation in Integration of Renewable Energy Systems)

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4899 KiB

Open AccessArticle

Grinding Fluid Jet Characteristics and Their Effect on a Gear Profile Grinding Process

by Philip Geilert, Carsten Heinzel and André Wagner

Inventions 2017, 2(4), 27; https://doi.org/10.3390/inventions2040027 - 25 Oct 2017

Cited by 11 | Viewed by 7217

Abstract

Profile gear grinding is characterized by a high level of achievable process performance and workpiece quality. However, the wide contact length between the workpiece and the grinding wheel is disadvantageous for the fluid supply to the contact zone and leads to the risk [...] Read more.

Profile gear grinding is characterized by a high level of achievable process performance and workpiece quality. However, the wide contact length between the workpiece and the grinding wheel is disadvantageous for the fluid supply to the contact zone and leads to the risk of locally burning the workpiece surface. For the reduction of both the thermal load and the risk of thermo-mechanical damage, the usage of a grinding fluid needs to be investigated and optimized. For this purpose, different kinds of grinding fluid nozzles were tested, which provide different grinding fluid jet characteristics. Through a specific design of the nozzles, it is possible to control the fluid flow inside the nozzle. It was found that this internal fluid flow directly influences the breakup of the coolant fluid jet. There are three groups of jet breakup (“droplet”, “wave & droplet”, and “atomization”). The first experimental results show that the influence of the jet breakup on the process performance is significant. The “wave & droplet” jet breakup can achieve a high process performance, in contrast to the “atomization” jet breakup. It can therefore be assumed that the wetting of the grinding wheel by the grinding fluid jet is significantly influenced by the jet breakup. Full article

(This article belongs to the Special Issue Modern Grinding Technology and Systems)

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7022 KiB

Open AccessArticle

Model Development for Optimum Setup Conditions that Satisfy Three Stability Criteria of Centerless Grinding Systems

by Fukuo Hashimoto

Inventions 2017, 2(4), 26; https://doi.org/10.3390/inventions2040026 - 21 Sep 2017

Cited by 13 | Viewed by 8486

Abstract

The centerless grinding process demonstrates superior grinding accuracy with extremely high productivity, but only if the setup conditions are properly set up. Otherwise, various unfavorable phenomena manifest during the grinding processes and become serious obstacles to achieving that high quality and productivity. These [...] Read more.

The centerless grinding process demonstrates superior grinding accuracy with extremely high productivity, but only if the setup conditions are properly set up. Otherwise, various unfavorable phenomena manifest during the grinding processes and become serious obstacles to achieving that high quality and productivity. These phenomena are associated with the fundamental stabilities of the centerless grinding system, so it is essential to keep the system stable by setting up the appropriate grinding conditions. This paper describes the development of a model for finding the setup conditions that simultaneously satisfy the three stability criteria of centerless grinding systems: (1) work rotation stability for safe operations; (2) geometrical rounding stability for better roundness; and (3) dynamic system stability for chatter-free grinding. The objective of the model development is to produce combinations of optimal setup conditions as the outputs of the model, and to rank the priority of the outputs using PI (performance index) functions based on the process aims (productivity or accuracy). The paper demonstrates that the developed model, named Opt-Setup Master, can generate the optimum setup conditions to ensure safe operations, better roundness and chatter-free grinding. It provides practical setup conditions as well as scientific parameters and fundamental grinding parameters. Finally, the paper verifies that the Opt-Setup Master provides the setup conditions that simultaneously satisfy all three stability criteria of the centerless grinding system. Full article

(This article belongs to the Special Issue Modern Grinding Technology and Systems)

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Inventions, Volume 2, Issue 4 (December 2017) – 11 articles

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